I do not speak german, but I can read and understand german (to a certain exctent)
The U53 is not mine...but its the old version of the U9, at least in norway.
It was sold from 1953 and had a 7 hp power Moto-St engine. It was not as though as the U9.
In norway the tractors was sold as gutbrod in 1951 when it arrived, with a green colour. This changed to moto standard in 1953, with the "blue" colour and red wheels, until mid 60`s. In the mid 60`s it went back to gutbrod, but kept the moto st colour.In the late 60`s it went over to the colour red and white with the name gutbrod.
I will ask him to send a picture of the tractor if its in one piece....
R